Electrical systems, such as those of an aircraft, may include variable frequency (VF) generators for power generation. These generators often include generator controllers that monitor and control the operation of the generator. In addition to the generator controller, these electrical systems often include overvoltage protection units that monitor voltage at a second point of protection.
Generator controllers, commonly referred to as generator control units (GCUs), regulate the operation of associated generators. For example, the GCU monitors the output voltage of the generator and regulates the current supplied to the exciter winding to regulate the output voltage to a desired value. In addition, the GCU provides protection against faults such as overvoltage faults. For example, if the circuit used to regulate the current supplied to the exciter winding fails, the GCU may trip a relay to disconnect power from the exciter winding, and may trip another relay to disconnect the generator output from a distribution bus to protect devices and components connected thereto.